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Suspicious Image Load (taskschd.dll) from MS Office

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Suspicious Image Load (taskschd.dll) from MS Office

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Identifies a suspicious image load (taskschd.dll) from Microsoft Office processes. This behavior may indicate adversarial activity where a scheduled task is configured via Windows Component Object Model (COM). This technique can be used to configure persistence and evade monitoring by avoiding the usage of the traditional Windows binary (schtasks.exe) used to manage scheduled tasks.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
logs-windows.*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Elastic
Host
Windows
Threat Detection
Persistence

Version: 100 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guide

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Rule query

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any where (event.category == "library" or (event.category ==
"process" and event.action : "Image loaded*")) and process.name :
("WINWORD.EXE", "EXCEL.EXE", "POWERPNT.EXE", "MSPUB.EXE",
"MSACCESS.EXE") and (dll.name : "taskschd.dll" or file.name :
"taskschd.dll")

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Scheduled Task/Job
- ID: T1053
- Reference URL: https://attack.mitre.org/techniques/T1053/

Rule version history

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Version 100 (8.5.0 release)

Formatting only

Version 6 (8.4.0 release)

Updated query, changed from:

library where process.name : ("WINWORD.EXE", "EXCEL.EXE",
"POWERPNT.EXE", "MSPUB.EXE", "MSACCESS.EXE") and event.action :
"load" and event.category : "library" and dll.name :
"taskschd.dll"

Version 4 (8.2.0 release)

Formatting only

Version 3 (7.12.0 release)

Updated query, changed from:

library where process.name in ("WINWORD.EXE", "EXCEL.EXE",
"POWERPNT.EXE", "MSPUB.EXE", "MSACCESS.EXE") and event.action ==
"load" and event.category == "library" and file.name ==
"taskschd.dll"

Version 2 (7.11.2 release)

Formatting only

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